Mokumon

Mokumon is a Smoke Digimon. It is a Digimon Baby which envelops its body with a smoke-like vapor. It is a unique Digimon whose DigiCore is bare, so it seems it covers its DigiCore with Smoke in order to protect it, and has an unusual way of life.[3] Because the Smoke was generated when its DigiCore was burned, it seems it is harmful neither to Mokumon itself or to others. Also, because it is still in the middle of digivolving, when it encounters an opponent it immediately flees. Then, it scatters the Smoke issuing from its body all around, and seizes the opportunity to escape when the opponent loses sight of it. As stated earlier, because it isn't particularly harmful, if you happen to see one it would be best to be quiet.[4]

Digimon Adventure 02: Tag Tamers

Digimon Tamers

A group of Mokumon were employed by Shibumi as his helpers when his consciousness was in the Digital World and his body was comatose in the Real World. One of the Mokumon takes Shibumi's form to enter the Real World and sneaks a Blue Card into a boy's card deck. Mitsuo Yamaki chases the Mokumon, thinking it was Shibumi, but the Mokumon disappears into a pile of smoke, revealing that it was really a Digimon. Two other Mokumon appear in Shibumi's library in the Water Space.